Letters: Explosive growth of world's cities

Sir: I should like to add a rider to Geoffrey Lean's timely article on the UN "city summit" in Istanbul ("What future for our cities?", 22 May). Posssibly the most threatening aspect of the explosive growth of cities is the demand this will make on energy resources.

The 1993 World Energy Council report Energy for Tomorrow's World predicted that in 25 years the demand for energy will have increased by 88 per cent over the 1990 level. Most of this increase will be the result of the spread of cities throughout the developing world. Soon after the turn of the century 300 million people will inhabit 21 megacities of over 100 million inhabitants and heading the list will be Hong Kong with 40 million. At the same time China is developing the world's largest linear city along 70 miles of the Pearl River. Much of the energy consumed by these cities will come from fossil fuels with their high carbon content.

Remembering that the UN Inter-Governmental Panel on Climate Change Scientific Committee states that, to be reasonably sure of halting global warming, we should cut back on carbon emissions by 60 per cent as against 1990 levels, then the energy demand created by this growth in urbanisation is by far the greatest threat facing the long-term stability of the planet.

Professor PETER F SMITH

Director

Sustainable Building Network

University of Sheffield